Review of the genus Omalium Gravenhorst, 1802 (Coleoptera: Staphylinidae: Omaliinae: Omaliini) of China

Five species groups are established for 19 species of the genus Omalium Gravenhorst, 1802 from China: Acutangulum group containing O. anguliferum sp. nov. (Sichuan, Shaanxi), O. rutilum sp. nov. and O. sectum sp. nov. (Yunnan); Caesum group containing O. pratense sp. nov. (Shaanxi); Oxyacanthae group containing O. alticola Cameron, 1941, O. cocleare sp. nov. and O. contiger sp. nov. (Yunnan, Sichuan), O. kurbatovi sp. nov. (Anhui), O. oxyacanthae (Gravenhorst, 1806) and O. schuelkei sp. nov. (Gansu, Sichuan); Rivulare group containing O. bambusaphilum sp. nov. (Jiangxi), O. confertum sp. nov. (Sichuan), O. tibetanum sp. nov. (Yunnan), O. lama sp. nov. (Qinghai, Sichuan), O. pseudojaponicum sp. nov. (Gansu), O. rougemonti sp. nov. (Zhejiang, Hubei, Shaanxi, Sichuan), O. smetanai sp. nov. (Yunnan) and O. xizangense Zheng & Pu, 2000 (Xizang); and unknown group containing O. chinese J.-K. Li, 1993, species with an uncertain taxonomic status described from Hejlongjiang. All 15 new species are described and illustrated, and their geographical distributions are mapped. A key to species known from China is provided. Omalium alticola is recorded from China for the first time.